From Science:
Being colorblind can be a good thing. Researchers studying capuchin monkeys in the forests of Costa Rica have shown that colorblind individuals are better at detecting camouflaged insects than are those that see a wider spectrum of colors. The finding is the first evidence from the wild that colorblindness confers advantages during foraging.
Capuchin monkeys and other New World monkeys of Central and South America vary in their ability to see color. Some capuchins, for example, have dichromatic vision–or are red-green colorblind–and see the world in shades of blue and yellow, whereas others have trichromatic vision similar to that of humans, allowing them to distinguish red, orange, yellow, and green. Biologists have long thought that better color vision is, well, better, especially because primates ostensibly use color to determine the ripeness of fruit, for example. So why has colorblindness persisted in these populations?
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